1. Field of the Invention
This invention relates to apparatus for gapping zipper chain. More specifically, this invention relates to apparatus for removing interfitting fastener elements in a section of zipper chain so that the chain may be severed adjacent the section and a slider and appropriate end stops may be applied to produce a zipper of discrete length.
2. Description of the Prior Art
The prior art is replete with showings of apparatuses for gapping zipper chain, usually in which the fastener elements take the form of plastic coils stitched onto the tape with or without the use of a filler cord. Typically, the prior art apparatuses comprise a punch adapted to come down and engage the central portion of the interlocked lines of fasteners and to fracture that portion against the edges of a slot beneath the punch and to move the broken portions downward through the slot away from the tapes. An example is shown in the Perlmann patent U.S. Pat. No. 3,368,269, granted Feb. 13, 1968.
Occasionally in the past, as shown in British Pat. No. 881,929 (1959), apparatuses for gapping zipper chain have taken the form of a pair of co-planar cutter wheels disposed on opposite sides of the chain as it is drawn through the apparatus, the cutter wheels adapted to shear off the heads of the fastener elements on the respective stringers.
Many of the apparatuses for gapping zipper chain in the prior art while they may have performed their function, have weakened or severed the lines of sewing threads in the section of the zipper in which the elements have been removed. This has produced a product wherein the attachment of the line of fastener elements, particularly near the terminals of the fastener elements of the zipper, has not been secure and may have resulted in the failure of prior zipper products.
Additionally, the apparatuses for gapping zipper chain in the prior art have not coped with the problem of severing the connector threads of the lines of fastener elements described above in the Abstract and as shown, for instance, in U.S. Pat. No. 3,414,948, issued Dec. 10, 1968 to Cuckson et al. Clearly, if these connector threads are not severed, then the complete removal of the scoops in the gapped area is not possible by the apparatus and additional hand work is necessary to make a clean gap.